September 2010
Surface Water Supply Index Report

Provided by the US Natural Resources Conservation Service
Bozeman, Montana

The SWSI is designed for areas that rely primarily on snowmelt runoff as the primary source of surface water. The SWSI accounts for snowpack, mountain precipitation, streamflow, reservoir contents, and soil moisture conditions. The SWSI can be used by irrigators, fisheries personnel, recreationists, and others who utilize surface waters. SWSI values are categorized as follows:

IDBasin NameValue
1Marias Above Tiber Reservoir0.4
1Marias Above Tiber Reservoir0.4
2Tobacco-0.8
2Tobacco-0.8
3Kootenai to Libby Dam-1.9
3Kootenai to Libby Dam-1.9
4Kootenai River below Libby Dam-2
4Kootenai River below Libby Dam-2
5Fisher River-0.8
5Fisher River-0.8
6Yaak River-0.6
6Yaak River-0.6
7North FK. Flathead River-0.1
7North FK. Flathead River-0.1
8Middle FK. Flathead River-0.5
8Middle FK. Flathead River-0.5
9South FK. Flathead River0.3
9South FK. Flathead River0.3
10Flathead at Columbia Falls-0.2
10Flathead at Columbia Falls-0.2
12Swan River0.9
12Swan River0.9
13Flathead River at Polson-0.2
13Flathead River at Polson-0.2
14Mission Valley0
14Mission Valley0
15Little Bitterroot River0
15Little Bitterroot River0
16Clark above Missoula2.8
16Clark above Missoula2.8
17Blackfoot River-0.7
17Blackfoot River-0.7
18Clark Fork above Missoula1.6
18Clark Fork above Missoula1.6
19Bitterroot River-0.3
19Bitterroot River-0.3
20Clark Fork River below Bitterroot River1
20Clark Fork River below Bitterroot River1
21Clark Fork River below Flathead River0.2
21Clark Fork River below Flathead River0.2
22Beaverhead River2.4
22Beaverhead River2.4
23Ruby River0.9
23Ruby River0.9
24Big Hole River1.6
24Big Hole River1.6
25Boulder River (Jefferson)3.7
25Boulder River (Jefferson)3.7
26Jefferson River2.2
26Jefferson River2.2
27Madison River-2.3
27Madison River-2.3
28Gallatin River1
28Gallatin River1
29Missouri River above Canyon Ferry1.1
29Missouri River above Canyon Ferry1.1
30Missouri River below Canyon Ferry1.3
30Missouri River below Canyon Ferry1.3
31Smith River2.1
31Smith River2.1
32Sun River-0.1
32Sun River-0.1
33Teton River-0.4
33Teton River-0.4
34Birch/Dupuyer0.3
34Birch/Dupuyer0.3
35Marias Below Tiber Reservoir1.9
35Marias Below Tiber Reservoir1.9
36Musselshell River2.4
36Musselshell River2.4
37Missouri River above Fort Peck1.6
37Missouri River above Fort Peck1.6
38Missouri River below Fort Peck0.1
38Missouri River below Fort Peck0.1
39Milk River3.9
39Milk River3.9
40Dearborn1.9
40Dearborn1.9
41Yellowstone River above Livingston0.4
41Yellowstone River above Livingston0.4
42Shields River2.2
42Shields River2.2
43Boulder River (Yellowstone)0.3
43Boulder River (Yellowstone)0.3
44Stillwater River0.9
44Stillwater River0.9
45Rock/Red Lodge Creeks3
45Rock/Red Lodge Creeks3
46Clarks Fork River-0.9
46Clarks Fork River-0.9
47Yellowstone River above Bighorn River0.3
47Yellowstone River above Bighorn River0.3
48Bighorn River below Bighorn Lake0.9
48Bighorn River below Bighorn Lake0.9
49Little Bighorn River0.4
49Little Bighorn River0.4
50Yellowstone River below Bighorn River0.5
50Yellowstone River below Bighorn River0.5
51Tongue River3.5
51Tongue River3.5
52Powder River-0.9
52Powder River-0.9
53Upper Judith River3.9
53Upper Judith River3.9
54Saint Mary River0.4
54Saint Mary River0.4